<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>

<body>

  <style>
    .one {
      /* 靠左对齐 */
      text-align: left;
    }

    .two {
      /* 居中对齐 */
      text-align: center;
    }

    .three {
      /* 靠右对齐 */
      text-align: right;
    }
  </style>

  <div class="one">第一句话</div>
  <div class="two">第二句话</div>
  <div class="three">第三句话</div>

</body>

</html>